the supports are molded resin fragile-looking but very strong all the same, the set screw is well in place and the settings are easy. careful anyway not to overload I do not venture to exceed 3 kilos per carrier.
the fixing screws are compatible for threading Bose speakers without problem.
provide a slight modification by drilling another hole 1cm below the second original hole to allow the support does not interfere with the speaker wire connection.
a very good product for less than 20 euros.